SANTA CRUZ, Calif. - A body believed to be a missing 8-year-old girl was found Monday inside a Dumpster at a complex in Northern California where she was last seen riding her scooter, and a 15-year-old boy has been detained in the case, police said.

Santa Cruz Police Chief Kevin Vogel said the body found by a detective Monday at a Santa Cruz artist community and housing center likely belongs to Madyson Middleton.

"We haven't positively identified her yet but believe she is probably Madyson Middleton," Vogel said.

He said a 15-year-old boy who lives in the complex was arrested around the same time the body was found and is being questioned.

Madyson Middleton vanished Sunday afternoon at Tannery Arts Center, where she lives with her mother.

She was last seen riding her new white scooter in the courtyard but about 5 p.m. her mother realized she was gone.

Madyson's parents met with investigators Sunday night and again Monday at police headquarters before speaking with reporters outside.

"I can't explain how difficult this is," the girl's mother, Laura Jordan, said earlier Monday.

Jordan said she's looked at surveillance video from their housing complex that watched Madyson's last minutes before she disappeared. Police have said she was last seen on video surveillance at 4:12 p.m.

Jordan walked the edges of the courtyard, and police twice conducted a door-to-door search of the entire complex, as well as a homeless resource center and shelter across the street.

Beyond the 8-acre property, searchers from throughout the state looked in boats, helicopters, on foot and bike, with dogs and cameras.

Authorities didn't send volunteers onto adjacent hiking and biking trails for fear of disturbing potential evidence, but hundreds of volunteers showed up and looked for her in neighborhoods and streets.

Authorities used dogs to search nearby woods and parks and the San Lorenzo River levee. Helicopters searched the forest and the coastline, and the U.S. Coast Guard scoured the ocean 2 miles from where she was last seen.

The 4-foot-tall, 50-pound child has long brown hair, which was pulled to the side in a braid, and dark eyes. She was wearing a purple dress, black leggings, black flip-flops and a black helmet.

She lived with her mother at the Tannery Arts Center, a public-private nonprofit project that includes 100 affordable loft apartments for artists and their families, a cafe, and dance and art studios on eight acres.

The property, a former leather tannery, is managed by The John Stewart Company. John Stewart, the company's chairman, said they turned the surveillance footage over to authorities Sunday night.

Site manager Warren Reed said the property is located in a very busy area, with a number of businesses and a major construction project nearby.